Field of the Invention
The present invention relates to a semiconductor device and a testing method therefor, and more particularly relates to a semiconductor device configured to detect disconnection or an increase of resistance of an internal power-supply line and a testing method for the semiconductor device.
Description of Related Art
A semiconductor device such as a DRAM (Dynamic Random Access Memory) includes various terminals including a power-supply terminal for receiving a power-supply potential from outside as well as a signal terminal for receiving an input signal from or supplying an output signal to outside. The power-supply terminal is connected to an external power-supply line provided outside of the semiconductor device to receive a power-supply potential from an external power supply device therethrough. The power-supply terminal is also connected to an internal power-supply line provided inside of the semiconductor device to convey the power-supply potential to each circuit part inside the semiconductor device therethrough.
Japanese Patent Application Laid-Open No. H7-225258 discloses a semiconductor device in which a bonding pad as a signal terminal and a lead terminal on a lead frame are connected to each other with a bonding tape or a bonding wire.
The internal power-supply line described above has a risk of the occurrence of disconnection or an increase of resistance. Since some troubles might occur on an operation of the semiconductor device due to such disconnection or an increase of resistance, it is preferable to detect them before shipment.
However, conventionally, there has been no effective method for realizing such detection in a direct manner. Instead, they have been detected in an indirect manner by determining whether the power-supply is normally supplied or not based on a result of an operation check of the semiconductor device. Although the disclosure of Japanese Patent Application Laid-Open No. H7-225258 discloses a method of determining whether bonding is properly performed or not, the method can only confirm whether the bonding is properly performed or not, and it cannot detect disconnection or an increase of resistance of the internal power-supply line.
The points described above are common problems in internal power-supply lines to which a certain type of voltage, such as a reference voltage, is supplied, not only in the internal power-supply line. Therefore, there has been desired a technique that can detect disconnection or an increase of resistance of an internal power-supply line in a direct manner.